1. Field of the Invention
The invention relates to a device for exchanging objects, in particular writing instruments, between two holders open on one side. For the transfer of an object, these holders are movable relative to one another by an approach in a plane extending substantially at right angles to their longitudinal axes. The object is retained in at least one holder by the cooperation of two retaining elements, one being a permanent magnet and the other a ferromagnetic element. In the retaining position, the retaining elements face one another close together, and in the separating position they are spaced farther apart from one another than in the retaining position.
2. Brief Description of the Prior Art
In a known device of this type (German Patent No. 32 26 455, corresponding to ANDERKA et al., U.S. Pat. No. 4,489,333) the object to be exchanged must be substantially in the shape of a regular convex-n-gon and must have a retaining element at each corner, each holder having a different retaining element in the receiving zone. In the retaining position, the retaining elements are located directly opposite one another. Hence, in removing the object from the one holder, the other holder is moved obliquely toward the holder having the object. A rotating of the object in its holder thereby displaces the retaining elements counter to one another. Meanwhile, in the position it has attained, the holder effecting the rotation has moved its retaining element into a position adjacent to a retaining element holding the object, so that the object is now held by this holder through magnetic action. By shifting this holder, the object can be moved out of the other holder, in which the retaining elements were spaced farther apart from one another.
In this known device, the object must have a quite specific, relatively complicated shape; moreover, the holder that is to receive the object must move obliquely toward the holder holding the object and then the initially obliquely moved holder must move away again, (now carrying the object), along a different, straight path. In other words, the holder must be moved under control along a relatively complicated path.
In another known device (German Patent No. 31 45 904, corresponding to BRANDT et al., U.S. Pat. No. 4,496,958) the holder that is moved toward the other holder for removing or inserting an object is moved back and forth along a straight line; i.e., it travels a very simple path of movement. In this device, the object in one holder is retained by two opposed leaf springs, which grip a short way around the object with their ends and press it against a stationary inside face, opposite the opening of the holder, of the receiving zone. The free ends of the leaf springs protrude somewhat in the direction of the transfer of the object to the other holder, and this other holder has two correspondingly embodied springs. If the object is held in one holder which approaches the other holder, then the free ends of the springs of the other holder, (because of the absence of an object therein), are spaced more closely together than the free ends of the first holder, (being forced apart by the object inserted therein). As a result, the free ends of the springs of the other holder come into contact with the outer circumference of the object, and upon further approach of the first holder to the other holder are spread apart. Because they are thus spread apart, the protruding free ends of the springs contact the first holder and force their way in between these springs and the object, until their free ends encompass the object and therefore pull it out of this first holder upon reversal of the motion of that holder.
When an object is inserted from the other holder into the first holder, the springs operate in the same manner as described above, but in that case the springs of the first holder force their way in between the springs of the second holder and engage the object.
In this known device, the location of the object in the holders is not defined precisely, because it is substantially determined by the properties of the two springs, which can change in the course of operation. Furthermore, its mechanical structure is relatively complicated and expensive.